1. Field of the Invention
The present invention relates to sports gear and in particular to sports gear that is capable of being manufactured to achieve specific performance criteria. The concepts of the present invention can be used for situations where “bat-ball” collisions are expected. For example, tennis rackets, baseball bats, hockey sticks and cricket bats may all benefit from the concepts of the present invention.
2. Description of the Related Art
Traditionally, sports gear of the above-type has been made of wood and/or metal. Some composite materials have also been used. For example:
United States Published Application 20090011877 to Iwata et al. is titled Bat for Baseball or Softball. It illustrates a bat having a core member with a depression at a portion to be a ball-hitting portion, and an elastic body attached to the depression and forming the ball-hitting portion. The elastic body is formed of urethane elastomeric foam having specific gravity of at least 0.45 and at most 0.60, JIS C hardness of at least 54 and at most 82, and modulus of elasticity in 300% elongation of at least 3.85 MPa and at most 5.6 MPa.
United States Published Application 20080287228 to Giannetti is titled Single Wall Ball Bat Including E-Glass Structural Fiber. The Giannetti application shows a single-wall ball bat with a series of layers or plies of unidirectional, two-dimensional, structural fibers. The plies are optionally layered upon each other in a lamina structure in which the fibers in one ply are oriented at opposing angles to the fibers in one or more neighboring plies. Low tensile modulus, two-dimensional E-glass fibers, oriented to provide desired durability, may be used to construct a substantial portion of the barrel or other regions of the ball bat.
United States Published Application 20040198539 to Sutherland et al. is titled Polymer Composite Bat. The Sutherland application describes a bat having of an elongated cylindrical handle portion for gripping, a cylindrical barrel portion for striking and a tapered cylindrical mid-section connecting the handle portion and the barrel portion, wherein at least the barrel portion is tubular and is constructed solely of a polymer composite material with a three-dimensional fiber reinforcement architecture Also disclosed are polymer composite baseball bats where the polymer composite material includes between 85% and 100% fiberglass reinforcement fibers, and/or where the central cavity is filled with a damping material such as polymeric foam or a low-density granular material, and/or where the bats are constructed of multiple layers of intertwined tubular braid forms using a precision molding process.
U.S. Pat. No. 7,575,527 to Davis et al. is titled Composite Bat Having a Single, Hollow Primary Tube Structure. It illustrates a bat formed of a single, hollow tube of composite material, wherein tubular “ports” extend through the hollow tube. The ends of the ports are bonded to the walls of the hollow tube. The ports improve the stiffness, strength, aerodynamics and comfort of the bat. In column 4, lines 34+ it is described how the tube is made of long fiber reinforced prepreg type material.
U.S. Pat. No. 6,634,969 to Forsythe et al. is titled Method of Tuning a Bat and a Tuned Bat. It teaches a method of tuning a bat that includes estimating a ball-bat interaction time, Ti, of an impact between a ball and the bat and tuning at least one desired mode of vibration in the bat produced by the impact. The desired mode of vibration is tuned by selecting properties of the bat so that the desired mode of vibration has a period approximately equal to 4/3 Ti. When a mode of vibration is so tuned, the energy the vibration transfers to a batted ball is optimized. A tuned bat has one or more of the desired modes that is approximately equal to 4/3 Ti, giving the bat a desirable bat performance factor and a desirable level of durability. Typically, the first hoop mode of vibration is given first priority during tuning of the bat. However, other modes of vibration, such as an axial bending mode of vibration may also be tuned to have a period approximately equal to 4/3 Ti. This is particularly true in composite bats where selecting the fiber angles can yield a different modulus of elasticity, for example, in the hoop direction than in the direction of the longitudinal axis of the bat, thereby tuning a hoop mode of vibration and an axial bending mode of vibration.
While the preceding published applications and patents may describe products that work well for their intended purposes, none teach the unique aspects of the present invention.
Two dimensional (“2D”) structures or laminates of fibers in thermoset polymeric matrices tend to be labor intensive and have high variability in performance. Shifts in material behavior in use can lead to difficulty in achieving a specific performance, difficulty in monitoring specifications and can be prone to tampering in an attempt to increase performance. Given the lack of performance measurements, the sports equipment made of these 2D methods tend to be quantified by feel or vibrational characteristics as opposed to more objective criteria. Further, inherent in a 2D structure is the lack of fibers oriented in a third dimension.
None of the preceding published applications or patents shows sports equipment with long discontinuous fibers in a long thin walled structure, or Long Fiber Thermoplastics (LFT).
One problem with sports equipment is termed a trampoline effect. In essence, the trampoline effect is caused by oscillations of the hollow cylindrical barrel of metal and composite bats. None of the preceding published applications or patents shows sports equipment designed to eliminate a trampoline effect. Laminated or layered bat structures often hide internal cracks that develop with time and that lead to softening and the trampoline effect. Quite often, laminated bats can initially pass the BBCOR (Ball Bat Coefficient of Restitution) test, but often flout this specification with bat use.
None of the preceding published applications or patents shows a method of making sports equipment designed to achieve selected objective performance characteristics.
A further disadvantage of using a two-dimensional hand-layup method of manufacture is the inconsistency and imprecision apparent in the manufactured product.
Bat rolling is a procedure that some can use to increase the trampoline effect of traditional thermoset/fiber laminates. This process is undesirable as it allows the user's to manipulate the bat in an unintended way.
Thus there exists a need for sports gear that solves these and other problems.